1. Field
One embodiment of the invention relates to a technology for increasing resolution of an image, and relates particularly to an image processor and an image processing method for increasing resolution of an image.
2. Description of the Related Art
Recent progress in the integration of a personal computer (PC) and a television provides more opportunities to view various types of videos on a high-resolution display with high definition (HD) exceeding standard definition (SD).
Video broadcast for SD televisions, video recorded on DVD, or the like has low resolution. Therefore, when users view video in HD size (especially, in full HD size, i.e., full HD resolution of 1920×1080 pixels), the resolution of the video is increased. To increase the resolution of an image, technologies, such as linear interpolation and cubic convolution interpolation, have been used to calculate pixel values of the image. With such technologies, however, a sharp image cannot be obtained.
In view of this, a super resolution technology has been studied, in which an image is expanded, and high-frequency component pixels are interpolated between pixels of the expanded image to obtain a sharp high-resolution image (see, for example, Japanese Patent Application Publication (KOKAI) Nos. 2008-067110 and 2008-146190). The conventional super resolution technology enhances the sharpness of video, and thus users can enjoy the sharp and clear video.
Videos are provided in various manners as, for example, via broadcasting including broadcasting satellite (BS) broadcasting, communication satellite (CS) broadcasting, digital terrestrial broadcasting, analog terrestrial broadcasting, and via the Internet. Accordingly, information amounts, noise amounts, and/or the like, of videos provided as such may differ for different types of videos. Therefore, when the super-resolution processing is equivalently performed on various videos, noise contained in, for example, the video provided via CS broadcasting having less information amount with respect to others becomes noticeable, thereby degrading the enhanced sharpness of video.
A method for sharpening video includes a sharpening process for sharpening appearance of video by sharpening an edge of the video, in accordance with various types of videos. However, such sharpening process entirely differs from the super resolution technology in that the super resolution technology on the other hand newly generates high-frequency component pixels. Thus, the sharpening technique used in the sharpening process cannot be used in the super resolution technology to adjust the sharpness of video in accordance with different types of videos.